Jack Burnham

... As Pamela Lee has recently reminded us: ‘systems theory was applied to emerging forms of digital media ... but it also served to explain art not expressly associated with technology today: conceptual art and its linguistic propositions, site-specific work and its environmental dimensions, performance art and its mattering of real time, minimalism even.’

One clue as to the reason for Burnham's subsequent invisibility may be this: "Disillusioned, he renounced systems aesthetics and retreated into an obscure, cabbalistic mysticism." I've run into more people in the tech world involved with various forms of mysticism (theosophy, Kabbalism) than in the art world. Burnham seems to have given up on art ever opening up to his tech utopianism rather than rejecting that latter.

Burnham went on to teach and chair several univeristy art and art history departments well into the '80s so he didn't completely disappear but the "cabbalistic mysticism" may give a clue as to his personality and how other artists and critics at the time related to his ideas and how they may now just be seen as 'sixties new age" which is how the term "new media" may strike a contemporary.

In any case, you can read his essay "Systems Esthetics" from the September, 1968 Artforum and decide for yourself here.